package tree;

import java.util.Objects;
import java.util.TreeMap;

/**
 * @author gy
 * @date 2019/6/7 7:36
 */
public class Trie {

    private Node root;
    private int size;

    public Trie() {
        root = new Node();
        size = 0;
    }

    public int getSize() {
        return size;
    }

    public void add(String word) {

        Node cur = root;
        for (int i = 0; i < word.length(); i++) {
            char c = word.charAt(i);

            if (Objects.isNull(cur.next.get(c))) {
                cur.next.put(c, new Node());
            }

            cur = cur.next.get(c);

            if (!cur.isWord) {
                cur.isWord = true;
                size++;
            }
        }
    }


    public boolean contains(String word) {
        Node cur = root;
        for (int i = 0; i < word.length(); i++) {
            char c = word.charAt(i);
            if (Objects.isNull(cur.next.get(c))) {
                return false;
            }
            cur = cur.next.get(c);
        }
        return cur.isWord;
    }

    public boolean isPrefix(String prefix){

        Node cur = root;
        for (int i = 0; i < prefix.length(); i++) {
            char c = prefix.charAt(i);
            if (Objects.isNull(cur.next.get(c))) {
                return false;
            }
            cur = cur.next.get(c);
        }
        return true;
    }


    private class Node {

        public boolean isWord;
        public TreeMap<Character, Node> next;

        public Node() {
            this(false);
        }

        public Node(boolean isWord) {
            this.isWord = isWord;
            next = new TreeMap<>();
        }


    }


}
